Why won't my laptop turn on on battery power?

Question

laptops

How to understand why the computer may not turn on from the battery? However, it can run on battery if you start it first from the network. Sleep, reboot, exit from sleep with the button and opening the lid work. But if you turn it off, remove the plug, then no matter how much you press the power button, it will not turn on. His only reaction is two barely audible clicks. It also happened that the mouse backlight could flicker if I hold down the power button.
It all started when I spilled my beer. Very little. There are no traces on the motherboard, there are no traces anywhere. The keyboard took the hit. Even in the first seconds, the audio output failed.
The battery is built in. There was no opportunity to get it, so he stood off for two days. After I was able to turn it on. It worked, the audio output too, but did not respond to the closing of the lid. After disassembly (then I saw that there were no traces of liquid below the keyboard), I dried it with a hairdryer and charged it. Now he turned on, and went to sleep when closed, woke up when opened. I repeat, all the buttons work, the battery too, but from the off state it does not turn on from the battery and only two clicks are heard. (It's too late to think about whether I did the right thing in this situation. And yes, the service is in the plans, but only if there are no clues to understanding this problem).